Current-Mode Analog Signal Processing Techniques

Current-mode analog signal processing has emerged as a compelling alternative to traditional voltage-mode approaches, particularly in applications demanding low power consumption, wide bandwidth and operation under reduced supply voltages. By encoding information as currents rather than voltages, designers exploit the inherently high impedance nodes and simple summation at current mirrors and current conveyors. Key building blocks include current mirrors for copying and scaling signals, current conveyors for high-speed current transfer, operational transconductance amplifiers (OTAs) for voltage-to-current conversion, and specialised current-mode filters for precision signal shaping. These circuits benefit from complementary metal–oxide–semiconductor (CMOS) scaling, allowing operation at sub-1 V supplies with microampere-level bias currents, which is essential for portable and implantable devices. Current-mode multipliers and dividers further extend functionality into nonlinear computation and frequency translation, enabling on-chip demodulation and adaptive filtering. Recent advances have also integrated current-mode elements into mixed-signal neuromorphic and in-memory computing architectures, where current summation maps naturally onto synaptic weight accumulation. Globally, these techniques underpin enhanced sensor interfaces, high-speed communication front ends, biomedical instrumentation and edge-computing accelerators, demonstrating the versatility and practical impact of current-mode analog processing.

Research from Nature Portfolio

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Research from all publishers

A highly energy-efficient analogue multiplier–divider compatible with digital code words has been realised in a 55 nm CMOS process for resistive random-access memory-based computing-in-memory macros. Using a current-mirror-based structure, the design achieves 8-bit precision for both multiplication and division while operating at 1.2 V and consuming under 6.15 µW. The 1.4 MHz bandwidth and 1 µs signal delay render it suitable for edge-computing tasks requiring compact real-time current-mode arithmetic.

A novel frequency discrimination technique utilises a multiplicative-integral network in conjunction with a linear transformation stage to extract instantaneous frequency parameters of modulation signals. This approach delivers a significantly wider discrimination bandwidth than conventional phase discriminators and, through inherent current-mode operations, achieves a 33.8 % reduction in noise-induced distortion on average. Crucially, the method exhibits low sensitivity to carrier-centre frequency errors, making it apt for low-accuracy clock environments.

A low-voltage, high-performance CMOS four-quadrant current-mode analog multiplier has been demonstrated using a submicrometre process. The circuit features high linearity across a broad input-current range and minimises parasitic capacitances to sustain MHz-level operation. Its simplicity of current-mode summation and subtractive techniques enables compact implementation in sensor readouts and communication demodulators under 1.8 V supplies.

Current-Mode Analog Signal Processing Techniques publication trend

The graph below shows the total number of articles in current-mode analog signal processing techniques across all publications each year (not limited to Nature Index journals).

Technical terms

Current mirror: A circuit that replicates an input current at one node to another, enabling scaling and summation of currents.

Current conveyor: A high-speed building block that transfers input currents to an output port with minimal voltage dependence.

Operational transconductance amplifier (OTA): A voltage-controlled current source whose transconductance can be tuned by bias current.

Four-quadrant analog multiplier: A device that produces an output current proportional to the product of two input currents, accommodating both polarities.

Bandwidth: The frequency range over which a current-mode circuit maintains specified performance, typically defined by its –3 dB point.

References

1. An Ultra-Low-Power Analog Multiplier–Divider Compatible with Digital Code for RRAM-Based Computing-in-Memory Macros. Micromachines (2023).
2. Research on Frequency Discrimination Method Using Multiplicative-Integral and Linear Transformation Network. Electronics (2024).
3. Low Voltage High Performance CMOS Current Mode Four-Quadrant Analog Multiplier Circuit. Radioengineering (2022).